Re: Client Certificates - re-opening discussion

[Mark Nottingham <[e-mail]>]

> On 18 Sep 2015, at 2:20 pm, Mike Belshe <[e-mail]> wrote:
> 
> In a strange twist of fate I find myself doing a lot of PKI work these days, and I've considered a fair bit about how client-certs might help with some of my application-level needs.
> 
> However, just like HTTP's basic-auth, I wonder HTTP or TLS level client-certs will just never be used?  My concern, of course, is that we build something that has a user experience similar to HTTP's basic-auth.  It's so bad that nobody can use it and authentication gets pulled into web pages (where ironically, it is less secure!).
> 
> Mark - you said there is "pain".  Is there a set of use cases to be solved here?  Let me know if I missed them - I may be able to contribute.  

By "pain", I meant that sites that use client certs (which turns out to be more common than many thought) want to update to HTTP/2, but can't.

Cheers,


> 
> My suspicion is that we really need crypto features moved up a level from the protocol, as it will be very difficult to make satisfactory user interfaces from the protocol level alone.  Perhaps for machine-to-machine auth it would be okay.
> 
> Mike
> 
> 
> 
> 
> 
> On Fri, Sep 18, 2015 at 10:05 AM, Mark Nottingham <[e-mail]> wrote:
> Hi Henry,
> 
> Thanks, but this is a much more narrowly-scoped discussion -- how to make client certs as they currently operate work in HTTP/2. At most, I think we'd be talking about incrementally improving client certs (e.g., clarifying / optimising the scope of their applicability -- and that really just is an example, not a statement of intent).
> 
> Cheers,
> 
> 
> > On 18 Sep 2015, at 11:53 am, Henry Story <[e-mail]> wrote:
> >
> >
> >> On 17 Sep 2015, at 23:10, Mark Nottingham <[e-mail]> wrote:
> >>
> >> Hi,
> >>
> >> We've talked about client certificates in HTTP/2 (and elsewhere) for a while, but the discussion has stalled.
> >>
> >> I've heard from numerous places that this is causing Pain. So, I'd like to devote a chunk of our time in Yokohama to discussing this.
> >>
> >> If you have a proposal or thoughts that might become a proposal in this area, please brush it off and be prepared. Of course, we can discuss on-list in the meantime.
> >>
> >> Cheers,
> >>
> >> --
> >> Mark Nottingham   https://www.mnot.net/
> >
> >
> > Apart from the proposals as the proposal by Martin Thomson
> > and the follow up work  referenced earlier in this thread
> > by Mike Bishop [1], I'd like to mention more HTTP centric
> > prototypes which would rely perhaps not so much on certificates,
> > but on linked public keys, that build on existing HTTP
> > mechanisms such as WWW-Authenticate, which if they pass security
> > scrutiny would fit nicely it seems to me with HTTP/2.0 .
> >
> > • Andrei Sambra's first sketch authentication protocol
> >   https://github.com/solid/solid-spec#webid-rsa
> >
> > • Manu Sporny's more fully fleshed out HTTP Message signature
> >   https://tools.ietf.org/html/draft-cavage-http-signatures-04
> >
> > These and the more TLS centric protocols require the user
> > agent to be able to use public/private keys generated by
> > the agent, and signed  or published by that origin, to
> > authenticate or sign documents across origins.
> >
> > This is where one often runs into the Same Origin Policy (SOP)
> > stone wall. There was an important discussion on
> > [e-mail] [1] and [e-mail]
> > entitled
> >
> >   "A Somewhat Critical View of SOP (Same Origin Policy)" [2]
> >
> > that I think has helped clarify the distinction between Same Origin
> > Policy, Linkability, Privacy and User Control, and which I hope
> > has helped show that this policy cannot be applied without
> > care nor can it apply everywhere.
> >
> > The arguments developed there should be helpful in opening discussion
> > here and elswhere too I think. In a couple of e-mails  in that
> > thread, I went into great detail showing how SOP, linkability and User
> > Control and privacy apply in very different ways to 4 technologies:
> > Cookies, FIDO, JS Crypto API and client certificates [3]. This shows
> > that the concepts don't overlap, two being technical and the two
> > legal/philosophical, each technology enabling some aspect of the
> > other, and not always the way one would expect.
> >
> > Having made those conceptual distinctions I think the path to
> > acceptance of solutions proposed by this group will be much eased.
> >
> > Looking forward to following and testing work developed here,
> >
> > All the best,
> >
> >       Henry
> >
> >
> > [1] • starting: https://lists.w3.org/Archives/Public/ietf-http-wg/2015AprJun/0558.html
> >    • most recent by Mike Bishop
> >    https://lists.w3.org/Archives/Public/ietf-http-wg/2015JulSep/0310.html
> > [2] https://lists.w3.org/Archives/Public/public-webappsec/2015Sep/
> > [3] https://lists.w3.org/Archives/Public/public-webappsec/2015Sep/0101.html
> >  which is in part summarised with respect to FIDO in a much shorter
> >  email
> >    https://lists.w3.org/Archives/Public/public-webappsec/2015Sep/0119.html
> >
> 
> --
> Mark Nottingham   https://www.mnot.net/
> 
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--
Mark Nottingham   https://www.mnot.net/